This invention relates to the field of engraving, and more particularly to engraving of gravure printing cylinders. Even more particularly, the invention relates to an engraving system comprising an engraving stylus and apparatus for causing the engraving stylus to engrave cells of accurately controlled size in the surface of a gravure printing cylinder.
An engraving stylus for such an engraving system is carried in a holder mounted on an engraving head supported against the surface of the workpiece by a shoe. The stylus holder is pivotally suspended within a magnetic field which oscillates under the influence of an AC head current modulated by a video signal. Variations in the head current drive the stylus into engraving against the surface of the cylinder. The depth of stylus penetration is controlled by variations in the video signal, as well as by settings of configuration parameters such as an AC gain, a video gain and a white offset. The white offset is the nominal spacing between the stylus tip and the surface of the workpiece when the head current goes to zero.
In order to engrave black cells, highlight cells and connecting channels of desired configuration, it has been necessary to undertake a tedious setup process prior to commencement of engraving. This process has involved trial and error engraving of test cells, inspection of the results and adjustment of the configuration control parameters. Frequently it has been necessary to repeat the process numerous times before satisfactory results have been achieved. It is a principal object of this invention to shorten that process.